4. elephant seals from antarctica dive into the ocean more than 1,500 meters deep at a time—nearly a mile. a seal can stay underwater for an hour or longer. to do that, the seal stores oxygen in its blood cells that is slowly released as it dives. the seal does not expend any extra energy releasing the oxygen stored in its blood cells. do you think passive or active transport is at work in the blood cells of the elephant seal? explain your answer.